Debunking Australia’s Biggest Diet Myths

November 14, 2018

Myth or fact: If you lose weight quickly you’ll gain back more weight


Studies investigating the rate of weight loss and consequential weight regain have found:

  • A rapid weight loss program followed by weight maintenance does not lead to gaining back more weight.
  • A greater initial weight loss compared to a more gradual weight loss approach results in greater short and long-term advantages.
  • When an individual achieves a large amount of initial weight loss they had greater longer-term weight loss and weight maintenance success.
  • It is important when weight loss is achieved; an active follow up weight maintenance program is adhered to that supports behavioural therapy, nutritional education and exercise.
  • People who lose weight rapidly compared to gradual weight loss are not more susceptible to weight regain.

Vink RG, Roumans NJ, Arkenbosch LA, Mariman EC, van Baak MA. The effect of rate of weight loss on long-term weight regain in adults with overweight and obesity. Obesity (Silver Spring). 2016 Feb;24(2):321-7. doi: 10.1002/oby.21346.

Paoli, A., Bianco, A., et al (2013). Long term successful weight loss with a combination biphasic ketogenic Mediterranean diet and Mediterranean diet protocol. Nutrients 5, 5205-521

Purcell K, Sumithran P, Prendergast LA, Bouniu CJ, Delbridge E, Proietto J. The effect of weight loss on long-term weight management: a randomised control trial. Lancet Diabetes Endocrinol. 2014;2(12):954-62.

Rolland C, Johnston KL, Lula S, Macdonald I, Broom J. Long-term weight loss maintenance and management following a VLCD: a 3-year outcome. Int J Clin Pract. 2014;68(3):379-87.

Nackers LM, Ross KM, Perri MG. The association between rate of initial weight loss and long-term success in obesity treatment: does slow and steady win the race? Int J Behav Med. 2010;17(3):161-7.

Myth or fact: A diet high in fat will make you fat


Studies researching the effect of high fat diets on weight have shown:

  • A diet too high in calories, no matter what the macronutrient composition, will cause weight gain.
  • A diet high in saturated fat could have negative health consequences, particularly in regards to heart health.
  • A diet high in healthy unsaturated fats will not cause you to be fat if the diet is still meeting caloric parameters.
  • Low carbohydrate high fat diets improve markers of cardiovascular risk.
  • An intake high in mono- and poly-unsaturated fats is supported by the science of CSIRO supporting healthy weight loss and management.

Noakes TD, Windt J. Evidence that supports the prescription of low-carbohydrate high-fat diets: a narrative review. 2017; 51(2):1-9.

Lim SS, Noakes M, Keogh JB, Clifton PM. Long-term effects of a low carbohydrate, low fat or high unsaturated fat diet compared to a non-intervention control. Nutrition, Metabolism & Cardiovascular Diseases. 2010;20(8):599-607.

Estruch R, Martinez-Gonzalez M, Corella D, Salas-Salvado J, Fito M, Chiva-Blanch G et al. Effect of a high-fat Mediterranean diet on bodyweight and waist circumference: a prespecified secondary outcomes analysis of the PREDIMED randomised control trial. Diabetes & Endocrinology. 2016;4(8):666-676.

Myth or fact: Keto diets aren’t sustainable


Despite a lack of research into ketogenic diets implemented in adults beyond 12 months, there has been evidence demonstrating the long-term benefits of ketogenic diets:

  • The most common health benefit long-term is a reduction in body weight and BMI.
    • Other Health benefits have included:
    • Decreased triglyceride levels and improved cholesterol
    • Decreased blood glucose levels
    • Increased HDL cholesterol (healthy cholesterol)
  • Administering a ketogenic diet for a relatively longer period of time did not produce any significant side effects.
  • A ketogenic diet high in poly-unsaturated and mono-unsaturated fats is favoured over saturated fats.

Dashti HM, Mathew TC, Hussein T, Asfar SK, Behbahani A, Khoursheed MA et al. Long-term effects of a ketogenic diet in obese patients. Exp Clin Cardiol. 2004;9(3):200-205.

Dashti HM, Al-Zaid NS, Mathew TC, Al-Mousawi M, Asfar SK, Behbahani AI. Long term effects of ketogenic diet in obese subjects with high cholesterol. Mol Cell Biochem. 2006;286(1-2):1-9.

Dashti HM, Mathew TC, Khadada M, Al-Mousawi M, Talib H, Asfar Sk et al. Beneficial effects of ketogenic diet in obese diabetic subjects. Mol Cell Biochem. 2007;302(1-2):249-56.

Sumi P, Proietto J. Ketogenic diets for weight loss: A review of their principles, safety and efficacy. Obesity Research & Clinical Practice. 2008;2:1-13.

Myth or fact: Eating after 8pm causes weight gain 


Studies exploring the effect of eating after 8pm on weight demonstrated:

  • Basal metabolic rate averages about the same at night as during the day, therefore the idea that metabolism becomes extremely slow at night time is actually a myth.
  • Eating after 8pm appears to be the blame of ‘weight gain’ when really it is that people overeat in the evening, consuming large amounts of calories and carbohydrates.
  • Overeating, no matter the time of day, causes weight gain due to exceeding daily energy requirements.
  • The time of dinner is not associated with energy intake of individuals.
  • Meal timing variations are not associated with BMI.
  • ‘Time’ is not a factor when it comes to weight gain yet consuming majority of the body’s calorie and energy food intake closer to the time of sleep can affect weight gain and sleep.

Kelly Glazer Baron, Phyllis C. Zee, MD, Kathryn J. Reid, ‘meal timing influences daily caloric intake in healthy adults’ Published 2014 October 2nd

Amber W. Kinsey,Michael J. Ormsbee, ‘the health impact of nighttime eating: old and new perspectives’, Published 2015 April 9th

Stephanie Eng, David A Wagstaff, Sibylle Kranz, ‘eating late in the evening is associated with childhood obesity in some age groups but not in all children: the relationship between time of consumption and body weight status in U.S. children’Published 2009 May 21st

Myth or fact: It’s not possible to lose weight without cutting out carbs


Studies exploring the role of carbohydrates in weight loss have found:

  • The most important factor in achieving weight loss is ensuring there is a calorie deficit achieved.
  • ‘Energy in’ from the diet needs to be less than ‘energy out’- the energy used throughout the day.
  • Therefore energy intake is more vital in weight loss than the macronutrient that is being restricted, e.g. carbohydrates.
  • There is no significant difference in weight loss when comparing low carbohydrate diets compared to low fat diets.
  • Low carbohydrate diets and low fat diets result in weight loss. Both diets lead to:
    • Decreased blood pressure, and improvements in blood sugar levels and insulin levels.

Kelly A Meckiling, Caitriona O’Sullivan, Dayna Saari, ‘comparison of a low-fat diet to a low-carbohydrate diet on weight loss, body composition, and risk factors for diabetes and cardiovascular disease in free-living, overweight men and women’ published 2004 June 4th.

Tay j, Thompson CH, Luscombe-Marsh ND, Wycherley TP, Noakes M, Buckely JD, Wittert GA, Yancy WS jnr, Brinkworth GD, ‘effects of an energy-restricted low-carbohydrates, high unsaturated fat/low saturated fat diet versus a high-carbohydrate, low-fat diet in T2D. A two-year clinical trial’, published 2017 December 20th.

Grant D Brinkworth, Manny Noakes, Johnathon D Buckley, Jennifer B Keogh, Peter M Clifton, ‘long term effects of a very-low carbohydrate weight loss diet compared with an isocaloric diet’ published May 2009 13th.

Myth or fact: A gluten free diet is better for your health


Studies investigating the healthy benefits of a diet containing gluten in comparison to a gluten free diet have shown:

  • The resistant starches in wheat and in gluten can assist in healthy colon bacteria, which has been shown to prevent some gastrointestinal cancers, improve inflammatory conditions and assist in preventing cardiovascular disease.
  • Individuals with high levels of lipids (fat molecules) in their blood have been shown to decrease these levels with a diet containing an increased amount of gluten.
  • There is an association between Coeliac Disease on a gluten free diet and an increasing BMI in individuals who are already overweight or obese.
  • Gluten free processed foods have a higher level of lipids, trans fats and salt compared to gluten containing products.
  • Studies have shown that gluten free processed foods such as breads and cereals are deficient in several nutrients including dietary fibre, folate, iron, niacin, riboflavin and thiamine.
  • For the general population, a gluten free diet is not necessary and it may have adverse affects:
    • Deficiencies of micronutrients
    • Increases in fat content of foods resulting in a higher risk of chronic disease development.
    • Increased financial costs
    • Social impairment
    • Restrictive eating 
  • Note: A gluten free diet can be used as nutrition therapy for several medical conditions such as Coeliac Disease.

 Gaesser, G. and Angadi, S. (2012). Gluten-Free Diet: Imprudent Dietary Advice for the General Population?. Journal of the Academy of Nutrition and Dietetics, 112(9), pp.1330-1333.

Niland, Benjamin and Brooks D Cash. “Health Benefits and Adverse Effects of a Gluten-Free Diet in Non-Celiac Disease Patients” Gastroenterology & hepatology vol. 14,2 (2018): 82-91.

Myth or fact: Diet shakes can replace a healthy, whole-food diet


Studies comparing the effects of diet shakes in comparison to wholefood diets (of equal nutritional composition) have shown:

  • Diet shakes should not be seen as a dietary equivalent to a wholefood diet.
  • Wholefoods promote energy balance and keep you feeling fuller for longer.
  • Hunger levels remain lower immediately after and over the following four hours after consumption after an intake of wholefoods in comparison to diet shakes.
  • Diet shakes have been shown to prompt stronger feelings of hunger and a heightened desire to eat.
  • Meals in the liquid form, dull the postprandial decline in hunger and increases food intake.
  • Blood sugar levels increase at a faster rate in response to consuming a diet shake in comparison to wholefoods.
  • Subsequently, insulin levels remain lower after the consumption of wholefoods in comparison to diet shakes.

S.M.Tieken, H.J.Leidy, A.J Stull, R.D.Mattes, R.A. Schuster, W.W. Campbell, ‘effects of solid versus liquid meal-replacement products of similar energy content on hunger, satiety and appetite-regulating hormones in older adults’, May 2007.

April J. Stull, John W. Apolzan, Anna E. Thalacker-Mercer, Heidi B. Iglay, Wayne W. Campbell, ‘liquid and solid meal replacement products differentially affect postprandial appetite and food intake in older adults’, published 2008 September 29th